Department of Nanomaterial Science, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan.
Chemphyschem. 2012 May 14;13(7):1638-48. doi: 10.1002/cphc.201100731. Epub 2012 Jan 17.
In this minireview, the features of low-frequency spectra within the frequency range 0-200 cm(-1) for aromatic and nonaromatic cation based ionic liquids obtained by femtosecond Raman-induced Kerr effect spectroscopy are reviewed. For aromatic cation based ionic liquids, the aromatic group of the cations is largely responsible for the spectral line shape due to their larger polarizability anisotropy volume and more polarizable nature than nonaromatic cations. The low-frequency Kerr spectra are also compared with the bulk properties of the ionic liquids. The differences in the relationship of the first moment of the low-frequency spectrum band and the bulk properties between the aromatic and nonaromatic cation based ionic liquids with respect to the natures of constituent ions and microscopic aspects are discussed. For aromatic cation based ionic liquids, the ionic region is more pronounced than the nonpolar region in their low-frequency Kerr spectra. In contrast, the ionic and nonpolar regions of nonaromatic cation based ionic liquids are likely to be captured due to the weaker signal of the cationic region. Also, the low-frequency Kerr spectra of the nonaromatic analogues are influenced by their weaker segregation as compared to aromatic cation based ionic liquids.
在这篇综述中，我们回顾了飞秒拉曼诱导克尔效应光谱在 0-200cm(-1) 低频范围内获得的芳香族和非芳香族阳离子基离子液体的低频谱特征。对于芳香族阳离子基离子液体，由于其较大的极化各向异性体积和比非芳香族阳离子更具极化性，阳离子的芳香族基团在很大程度上决定了光谱形状。我们还将低频克尔光谱与离子液体的体性质进行了比较。讨论了不同性质的离子和微观方面对低频谱带的第一矩与芳香族和非芳香族阳离子基离子液体体性质之间关系的影响。对于芳香族阳离子基离子液体，其低频克尔光谱中离子区域比非极性区域更为明显。相比之下，由于阳离子区域的信号较弱，非芳香族阳离子基离子液体的离子和非极性区域可能会被捕获。此外，与芳香族阳离子基离子液体相比，非芳香族类似物的低频克尔光谱受到它们较弱的分离影响。
